Synthesis, Redox and Structural Properties of Cystine-Cyclopeptides Containing the Active-Site of the Thioredoxin Superfamily

Thioredoxin (TRX), thioredoxin-reductase (TRR), protein disulfide isomerase (PDI) and glutaredoxin (GRX) belong to the TRX family of thiol-disulfide oxidoreductases [1]. The active-site sequence motif common to all members of this family is Cys-Xaa-Yaa-Cys. PDI is the strongest oxidant of the family (E0 = -0.110 V) and is known to be involved in in vivo oxidative folding of proteins. In vitro it catalyzes the refolding of reduced or scrambled RNase A [2].